1. Field of the Invention
The invention relates generally to a lock or securing system, especially a door lock, and is directed more particularly to an electrically-controlled lock for a revolving door.
2. Prior Art
Selectively-activated, electrically-controlled locks for revolving doors are known in the prior art which include one or more locking members vertically extensible to prevent rotation of the door. Examples of such locks are disclosed in the following U.S. patents:
______________________________________ 1,455,677 Stevens May 15, 1923 1,493,690 Martin May 13, 1924 1,952,393 Tigue Mar. 27, 1934 1,979,497 Schneider et al. Nov. 6, 1934 2,186,385 Lockhart June 9, 1940 2,695,574 Ceci Nov. 30, 1954 3,045,615 Atchison July 24, 1962 3,285,209 Pace Nov. 15, 1966 4,060,935 Miller et al. Dec. 6, 1977 4,341,165 Calandritti et al. July 27, 1982 ______________________________________
Lockhart discloses a lock controlled by a switch-activated motor which causes a pair of levers to pivot and force a pin to register in one of several holes in an annular channel provided in a circular plate located above the revolving door. In the lock of Schneider et al., a biased bolt is released by a solenoid to enter one of several holes in a circular element attached to the top of the doors. The control circuit and switches permit the bolt to be inserted into and retracted from the hole.
Instead of a circular element as used in Schneider et al., Pace uses a curved cam plate attached to the door's central column. A solenoid-controlled, biased plunger is forced into one of four holes in the periphery of the plate to lock the door, with separate solenoids releasing and retracting the plunger.
Stevens uses an electrically-controlled trigger to push down a post which forces four horizontally-movable, biased rods between vertical bars. A screw jack is used to move the post upwardly to permit withdrawal of the rods by cooperating springs.
Martin provides a vertically movable shaft having a shaped head portion, retained by an electrically-actuated latch, which is permitted to drop into a similarly-shaped recess to lock the revolving door. Ceci uses a cable-operated system to vertically extend bars between the doors to prevent rotation thereof.
The other patents describe other types of locks for a revolving door. Calandritti et al., Miller et al. and Atchison each uses a drive motor to prevent door rotation, and Tigue uses meshing gear sectors.